The invention relates to a light beam receiver, particularly a hand-held passive target plate for the visible laser beam of a laser positioning device.
Such light beam receivers are used on construction sites for marking objects based on a programmed laser beam moved over a surface or radiated and for aligning the laser positioning device based on a previous marking on the object.
According to European Patent no. 508590, hand-held active target plates comprise an electro-optical sensor line with a signal emitter controlled by the alignment of the target plate with the laser beam and marking indices arranged on the edges. Such active target plates require a power source for the sensor and are, therefore, characterized by limited reliability in general activities on the construction site.
According to U.S. Pat. No. 5,818,633, hand-held passive target plates contain fresnel lens formed in a compact, transparent plastic body that visibly expand the punctuate-occurring laser beam. According to U.S. Pat. No. 5,710,647, the impinging laser beam is split by an axicon formed in the transparent plastic body and the two partial beams are displayed, via holograms, for the purpose of beam expansion, onto two component surfaces of different brightness, whereby alignment is possible respective of the brightness difference. Production of the precise, optically-active structures is relatively expensive.